Variable Impedance Power Supply Inrush Current Control
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Solution Overview
Problem
Power supplies face issues with inrush current when starting or connecting loads, leading to energy wastage due to high resistance from negative temperature coefficient thermistors, which are used to suppress inrush current but are inefficient during normal operation.
Innovation Solution
A power supply apparatus with variable circuit loop impedance, incorporating a power conversion unit, capacitors, a switch unit, and a switch control unit that adjusts capacitor impedance based on operational mode to reduce inrush current and energy wastage, potentially eliminating the need for negative temperature coefficient thermistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a negative temperature coefficient thermistor is used to suppress inrush current, then inrush current is reduced, but energy wastage increases during normal operation due to high resistance
Solution Approach 1:
The patent implements dynamic impedance adjustment by using a switchable capacitor configuration. During startup, capacitors are connected in series to provide high impedance for inrush current suppression. During normal operation, the switch changes the configuration to parallel connection, providing low impedance to minimize energy loss. This dynamic reconfiguration allows the circuit to adapt its impedance characteristics based on operational requirements.
Solution Approach 2:
The patent changes the electrical parameter (impedance) of the capacitor circuit from fixed to variable. By using a switch to alter the connection topology between capacitors, the overall impedance can be changed between two distinct states: high impedance (series connection) for inrush current suppression and low impedance (parallel connection) for normal operation with minimal energy loss.
2Reliability
If a negative temperature coefficient thermistor is used to suppress inrush current, then inrush current is reduced, but device complexity increases
Solution Approach 1:
Instead of relying on the temperature-dependent resistance characteristic of thermistors, the patent changes the impedance parameter through switching capacitor configurations. This approach replaces a passive component with inherent temperature-dependent behavior with an active switching mechanism that provides deterministic impedance control, potentially simplifying the overall device design and improving predictability.
3Reliability
If capacitor impedance is kept high to suppress inrush current, then inrush current is reduced, but power conversion efficiency decreases during working mode
Solution Approach 1:
The patent implements dynamic impedance adjustment by using a switchable capacitor configuration. During startup, capacitors are connected in series to provide high impedance for inrush current suppression. During normal operation, the switch changes the configuration to parallel connection, providing low impedance to minimize energy loss. This dynamic reconfiguration allows the circuit to adapt its impedance characteristics based on operational requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces inrush current and energy wastage by dynamically adjusting capacitor impedance, improving efficiency and potentially reducing the need for thermistors, thus enhancing power supply performance.
Implementation Method 1
The first capacitor is electrically connected to the power conversion unit. The second capacitor is electrically connected to the power conversion unit and the first capacitor. After the first switch control unit receives the power starting signal, the first switch control unit turns on the first switch unit, so that an overall capacitor impedance formed by the first capacitor and the second capacitor is smaller than a first capacitor impedance formed by the first capacitor.
Data Source
AI summary
When a power conversion unit is in a working mode, the power conversion unit converts an alternating current power from an alternating current power supply apparatus into a direct current power. Then, the power conversion unit sends a power starting signal to a first switch control unit. After the first switch control unit receives the power starting signal, the first switch control unit turns on a first switch unit, so that an overall capacitor impedance formed by a first capacitor and a second capacitor is smaller than a first capacitor impedance formed by the first capacitor. When the power conversion unit is not in the working mode, the first switch control unit turns off the first switch unit, so that the overall capacitor impedance is equal to the first capacitor impedance.